lib: introduce wiringPi nit wrapper

Signed-off-by: Alexandre Terrasa <alexandre@moz-code.org>
examples: add wiringPi wrapper examples

Signed-off-by: Alexandre Terrasa <alexandre@moz-code.org>
lib: add sr595 abstraction

Signed-off-by: Alexandre Terrasa <alexandre@moz-code.org>
example: add sr595 example

Signed-off-by: Alexandre Terrasa <alexandre@moz-code.org>